The invention relates to a process for the preparation of a fine-particled, stable, pharmaceutical or cosmetic dispersion consisting of an aqueous phase and an organic phase which is insoluble or not completely soluble in water.
Pharmaceutical and cosmetic emulsions are usually prepared by a procedure in which the fatty phase, or organic phase, which has been melted at temperatures of 60.degree. to 70.degree. C., and the entire aqueous phase, which has been brought to the same temperature, are combined, and pre-emulsified, in a stirred kettle and the crude emulsion thus obtained is cooled to 20.degree. to 40.degree. C. in a jacket cooler or flow-through cooler and then very finely dispersed with a high-pressure homogeniser.
The disadvantage of this process is that the entire batch must first be heated and, after pre-emulsification, must necessarily be cooled again in order then to bring the entire emulsion, which frequently has only a small amount of disperse fatty phase, to the desired fineness by means of high-pressure homogenizers. Such an energy-intensive temperature program is necessary, since when the surface are of the disperse phase is increased by the homogenization, the stability of the emulsion at elevated temperature and with simultaneous exposure to mechanical stress is insufficient. Enforced stability to heat and shearing stresses by emulsifiers is not permitted, since the amount and nature of the emulsifier system are to be selected according to pharmacological view points and from the point of view of the storage stability of the end product, and not according to the far higher stability requirements during production.
The invention is based on the object of developing a process for the preparation of pharmaceutical and cosmetic emulsions, which have a more favorable energy balance, whilst giving the same yield.